The next generation network (NGN) is a hot research topic in the current communication standard field. The NGN integrates fixed communications with mobile communications by adopting packet technologies, such as the Internet protocol (IP) technology and so on, as the bearer network technology. The NGN can provide more abundant multimedia services, such as some emerging services with real-time requirements (e.g., VoIP, video conference, multimedia distance teaching, video-on-demand or the like), and these services require that the communication network could provide efficient end-to-end quality of service (QoS) support; meanwhile, the users have increasingly high requirements on the QoS of the network. Therefore, how to provide the end-to-end QoS becomes one of the core issues of the NGN.
The international telecommunication union-telecommunication standardization sector (abbreviated as ITU-T) is the telecommunication sector of the international telecommunication union (abbreviated as ITU), which formulates standards related to resource and admission control. In the latest resource and admission control functions (abbreviated as RACF) draft published by the ITU-T, there is provided an RACF functional framework. As shown in FIG. 1, the RACF is composed of two parts which are respectively a policy decision functional entity (abbreviated as PD-FE) and a transport resource control functional entity (abbreviated as TRC-FE), where the TRC-FE interacts with the transport functions via the Rc, and interacts with a transport resource enforcement functional entity (abbreviated as TRE-FE) via the Rn, moreover, the PD-FE interacts with the TRC-FE via the Rt, interacts with a customer premises network (abbreviated as CPN) via the Rh, interacts with a policy enforcement functional entity (abbreviated as PE-FE) via the Rw, interacts with service control functions (abbreviated as SCF) of the service layer via the Rs, interacts with network attachment control functions (abbreviated as NACF) via the Ru, and interacts with other NGNs via the Ri interface.
In addition, the PD-FE is transport technology-independent and is independent of the SCF as well. The PD-FE makes a final decision of resource and admission control based on network policy rules, service information provided by the SCF, transport layer subscription information provided by the NACF, and resource availability decision results provided by the TRC-FE.
The TRC-FE is service-independent, but is transport technology-dependent. The TRC-FE is responsible for collection and maintenance of the transport network information and resource status information. After receiving a resource request from the PD-FE, the TRC-FE executes resource-based admission control based on QoS, priority requirements, resource availability information and transmission-related policy rules.
The transport layer is composed of the PE-FE and the TRE-FE. The PE-FE, as a packet-to-packet gateway which may be located between a CPN and an access network, between an access network and a core network, or between networks of different operators, executes the policy rules issued by the PD-FE. The PE-FE is a key node which supports dynamic QoS control, port address translation control and network address translation (abbreviated as NAT) traversal. The TRE-FE executes transport resource policy rules issued by the TRC-FE, and its scope, functions and Rn interface need further research, which are not in the research scope of the R2 stage.
The telecommunication and Internet converged services and protocols for advanced networking (TISPAN) proposes a resource and admission control subsystem (RACS) from the aspect of fixed access, to solve the QoS problem of the NGN bearer network. The TISPAN divides the NGN framework into a service layer and a transport layer, and introduces the RACS and a network attachment subsystem (NASS) to the transport control layer. The RACS solves the QoS problem of the NGN bearer network, and the NASS is responsible for providing independent user access management for the upper service layer. The main functions of the TISPAN RACS are similar to those of the ITU-T RACF.
The functional framework of the TISPAN RACS is shown in FIG. 2. The RACS, which is a part of the NGN, associates the resource requirements of the service layer (e.g. IMS) with the resource allocation of the bearer network layer. The RACS mainly realizes functions such as policy control, resource reservation, admission control, NAT traversal or the like. The RACS provides the control services of the transport layer for the application functions (AF) through a series of QoS policies, so that a user equipment (UE) can obtain the required service with a guaranteed QoS.
The RACS is composed of two entities: a service-based policy decision function (SPDF) and an access-resource and admission control function (A-RACF) which will be respectively described as follows.
The SPDF provides unified interfaces for the application functions, shields the underlying network topologies and specific types of access, and provides service-based policy control. The SPDF selects local policies according to a request from an application function (AF), and maps the request into QoS parameters which are transmitted to the A-RACF and a border gateway function (BGF), so as to control the corresponding resources.
The A-RACF controls the access network and has functions of admission control and network policy convergence. The A-RACF receives a request from the SPDF, and then accepts or refuses the request for the transport resources to realize the admission control based on the access network policies. The A-RACF obtains network attachment information and user QoS list (profile) information from the NASS via an e4 interface, so as to determine available network resources according to the network location information (for example, physical node address of an accessed user); meanwhile, when dealing with the resource allocation request, the A-RACF checks whether the requested bandwidth information is consistent with that described in the user access list (profile).
The transport layer is composed of two functional entities: a border gateway function (BGF) and a resource control enforcement function (RCEF).
The BGF is a packet-to-packet gateway and can be located between an access network and a core network (to realize a core border gateway function), or between two core networks (to realize an interconnection border gateway function). The BGF realizes functions including NAT traversal, gating, QoS marking, bandwidth limiting, usage measurement and resource synchronization under the control of the SPDF.
The RCEF executes the layer 2/layer 3 (L2/L3) media stream policies transmitted via the Re interface from the A-RACF to realize functions such as gating, QoS marking, bandwidth limiting, and the like.
The 3rd Generation Partnership Project (3GPP) proposes a policy control and charging (PCC) solution from the aspect of mobile access to realize the resource and admission control function. The PCC, which is placed between the service control layer and the access/bearer layer, realizes a certain QoS control mechanism aiming at the characteristics of the mobile access network. The main functions of the PCC are realizing policy control based on the customized information of the users and performing charging control based on the service data flow.
The functional framework of the 3GPP PCC is shown in FIG. 3. The policy and charging rules function (PCRF) comprises policy control deciding and charging by flow control functions. The PCRF provides the network control functions regarding PCEF-oriented service data flow-related detection, gating, QoS and charging by flow (except for the credit management).
The PCEF comprises functions including service data flow detection, policy execution, and the charging by flow, and resides in a gateway (GW). The PCEF provides service data flow detection, user plane flow processing, trigger control plane session management, QoS execution, service data flow measurement and interaction with the charging system. A subscription profile repository (SRR) stores user subscription data. The OCS and the OFCS are respectively online charging system and offline charging system, wherein, the OCS comprises a customized applications for mobile network enhanced logic service control point (CAMEL SCP) and a service data flow based credit control.
Multimedia service bandwidth in a mobile network is not as guaranteed as that in a fixed network or in a wireless local area network (WLAN) such as the WiFi, and the services provided by the multimedia broadcast/multicast service (MBMS) and the packet-switched streaming service (PSS) in the mobile network are not as abundant as IPTV services; therefore, mobile users can consider accessing IPTV services at home. As fixed networks and the mobile networks are deployed with respective resource control systems and service functions, therefore, when a mobile user (Dual-mode mobile terminal) accesses via a fixed network and accesses IPTV services thereon, in order to provide QoS support, the RACF/RACS in the fixed network needs to interact with the PCRF in the mobile network. The networking solution is shown in FIG. 4, and the PCRF is connected with the mobile user information repository. FIG. 5 further provides an interaction diagram between the RACF/RACS and the PCC. The RACF/RACS is connected with the PCC via an interface S9′, which is mainly used for information interaction between the RACF/RACS and the PCC. As there are tremendous differences among the RACF, the RACS and the PCC in the aspects of framework, network coverage, and related node type, in the prior art, the functions supported by the RACF, the RACS and the PCC cannot ensure quality of user service experience in the scenes illustrated in the FIG. 4/FIG. 5. In the prior art, the problem that the RACF, the RACS and the PCC cannot work cooperatively and interactively urgently needs a solution.